Optimizing Nuclepore filter penetration for length and fractal dimension characterization of non-spherical particles

摘要

Effective length, an important parameter responsible for the respiratory deposition due to interception, of non-spherical particles is measured up to now mainly after sampling with off-line image analysis. Besides, fractal dimension, is a crucial parameter of the quality control of nanomaterial productions (e.g. by flame reactors). By combination of a DMA (differential mobility analyzer) with a 1 or 3 μm pore diameter Nuclepore filter, a new method for differentiating nanoparticles with different mass-mobility fractal dimensions, Dfm, in few minutes was developed and validated experimentally and theoretically. In the method, the DMA first classifies the particles to be monodisperse and then penetration of the monosized particles through the Nuclepore filter is measured. At the same mobility diameter, it was observed that the compact NaCl had the highest penetration followed by partially sintered silver (Ag) aggregates and then the loose Ag and soot agglomerates (data won't be shown here). The result indicates that the higher interception by the filter is correlated to the more elongated shape of the particles.